Published on 7 June 2022
Share Tweet  Share

Evidence-neglect: a major barrier to government health and climate ambitions

Political dimensions of decision-making can often eclipse the evidence to the detriment of positive societal outcomes. Evidence-neglect is a major inhibitor and barrier to achieving global health, wellbeing, and climate change ambitions, writes Dame Professor Theresa Marteau.

Recent UK governments have set some audacious ambitions to improve the nation’s health and tackle climate change. These include halving childhood obesity by 2030, eradicating smoking by 2030, increasing by five the number of years we live in good health by 2035 and achieving net zero carbon emissions by 2050.

  • None of these ambitions is on course.
  • Childhood obesity is on track to double, not halve, by 2030.1
  • Smoking eradication is on track sometime after 2050, not by 2030.2
  • Living five more years in good health is, by one estimate, on track for 2215, not 2035.3
  • The UK sixth carbon budget is on track to being missed by “a huge margin”.4


There are many possible reasons.

Chief amongst these is the neglect of evidence in the policies designed to achieve the ambitions. Put simply, these failures are baked-in.

Achieving each of these ambitions requires sustained changes across all social groups in several sets of behaviour including what we eat, drink, whether we smoke, and how we travel. Achieving such change is difficult, requiring many interventions that change the environments or systems that too readily cue, reinforce and maintain unhealthier and unsustainable behaviours.  Interventions that tackle the affordability, availability and marketing of unhealthier (vs healthier) and unsustainable (vs sustainable) products and activities show the largest effects, evidence summarised in widely disseminated publications and reports.2; 5-13

Yet too little of this evidence has informed obesity, smoking or climate policies to date thus jeopardising their ambitions.1,2,3,14


At least three sets of factors militate against more effective interventions making their way into policies.

First, the incentive structure for politicians favours setting ambitious policy goals but disfavours the policies that could achieve them. Fear of electoral damage is one reason.15 Take taxes on tobacco, alcohol, junk food and carbon emissions: unpopular with the public – but amongst the most effective interventions for improving health and the climate.16; 17 The political unpalatability of such taxes is illustrated in the fate of two recommendations to improve our diets  – a tax on sugar and on salt, included in a report commissioned by the Department for Environment, Food and Rural Affairs. (11) Asked to comment on the day of publication, the Prime Minister said:

I’m not attracted to the idea of extra taxes on hard working people.18

Two years analysis based on robust evidence dismissed on its first exposure to politics.  

Ideologies and interests can also militate against effective policies. Political philosophies that frame behaviour as a matter of personal responsibility underplay robust evidence on the powerful role of environments in shaping behaviour despite peoples’ desires to behave differently. The UK government strategy for net zero illustrates this with its focus on technology for reducing emissions to the neglect of behaviour change, without which net zero cannot be achieved by 2050.19 Commenting on the removal from its website of a commissioned paper on behaviour change strategies for net zero, a government spokesperson said:

This was an academic research paper, not government policy. We have no plans whatsoever to dictate consumer behaviour in this way. For that reason, our Net Zero Strategy published yesterday contained no such plans.20

Such a frame of personal responsibility is also used by industries when their interests conflict with effective policies that would reduce consumption of their products. As enshrined in the book title Merchants of Doubt21, industries such as those selling fossil fuels, tobacco, alcohol and junk food also cast doubt on the effectiveness of policies that would reduce their sales, as well as lobbying governments to persuade them of the business case for the status quo.  Using these tactics, industry interests have prevailed over effective policies in the UK for reducing smoking,2 consumption of alcohol,22 and junk food.23

Policy evaluation – or rather the lack of it – is the third set of factors militating against more effective policies. The incentives, ideologies and interests that sometimes conflict with effective policies are to be expected. But the safety-net of policy evaluation – designed to ensure public spending improves people’s lives i.e. is effective – is failing. A recent National Audit Office report found that only 8% of major government spending projects in 2019 had evaluation plans.24

….government will have to do more to address the systemic barriers to effective evaluation and the application of evaluation evidence to policy-making. Otherwise it will not be able to ensure evaluations drive improved outcome.24

How might these failings be remedied?

There are no quick fixes.

King and Crewe in Blunders of our Governments15 and more recently Jonathan Slater in Fixing Whitehall’s Broken Policy Machine25 suggest system-level changes for more effective policymaking including changes that reward policy success and increase the publicly accountability of policymaking. Engaging citizens more in policymaking and strengthening existing systems of policy evaluation could each contribute.

Engaging citizens more in policymaking could help reduce the political costs of introducing effective but unpopular policies. Such engagement ranges from communicating the effectiveness of planned policies to running citizen assemblies to inform policy plans. The weight of evidence shows people will trade-off their dislike of a policy to achieve a valued outcome.26 For example, a policy that increased the price of alcohol by introducing a minimum unit price of £1 was supported by 63% of people when informed of its effectiveness at reducing crime and hospital admissions, compared with 43% when not given this information.27 Citizen assemblies on climate change, which entail acquainting participants with evidence of the effectiveness of different policy options, consistently recommend more ambitious policies for net zero than those adopted by their governments.5

UK government guidance on policymaking accords a central role to evidence in evaluating the three stages of policymaking – design, implementation, outcome.28, 29

But this guidance is not often followed.24, 30 Mandating evaluations and their publication at each of these stages would open policymaking to greater public scrutiny and in doing so should decrease the neglect of evidence central to policy success. The first two stages are vital to the success of a policy.

The first stage – policy design – would be strengthened by requiring quantified estimates of the likely contribution of each policy towards achieving the policy ambition. The second stage – implementation –  would be strengthened not only by requiring progress to be monitored but also by requiring action when progress is off course.  

These two changes – engaging citizens more in policymaking and requiring published evaluations at all three stages of policymaking  – could give evidence to the central role in policymaking needed to realise major government ambitions. A hypothesis worth testing?



3Healthy life expectancy target: the scale of the challenge | The Health Foundation


5Marteau TM, Chater N, Garnett EE. Changing behaviour for net zero 2050. bmj. 2021 Oct 7;375.

6Whitmarsh L, Poortinga W, Capstick S. Behaviour change to address climate change. Current Opinion in Psychology. 2021 Dec 1;42:76-81.

7Marteau TM, Hollands GJ, Pechey R, Reynolds JP, Jebb SA. Changing the assortment of available food and drink for leaner, greener diets. bmj. 2022 Apr 13;377.




11National Food Strategy Part 2 Dimbleby

12Marteau TM, White M, Rutter H, Petticrew M, Mytton OT, McGowan JG, Aldridge RW. Increasing healthy life expectancy equitably in England by 5 years by 2035: could it be achieved?. The Lancet. 2019 Jun 29;393(10191):2571-3.

13Marteau TM, Rutter H, Marmot M. Changing behaviour: an essential component of tackling health inequalities. BMJ. 2021 Feb 10;372.

14Theis DR, White M. Is obesity policy in England fit for purpose? Analysis of government strategies and policies, 1992–2020. The Milbank Quarterly. 2021 Mar;99(1):126-70.

15King A, Crewe I. The blunders of our governments. Simon and Schuster; 2014 Sep 4.

16Bloomberg MR, Summers LH, Ahmed M, et al. Health taxes to save lives: employing effective excise taxes on tobacco, alcohol, and sugary beverages: the Task Force on Fiscal Policy for Health. New York: Bloomberg Philanthropies, 2019.

17Engström G, Gars J, Krishnamurthy C, Spiro D, Calel R, Lindahl T, et al. Carbon pricing and planetary boundaries. Nat Commun. 2020 Sep 17;11(1):4688.




21Oreskes N, Conway EM. Merchants of doubt: How a handful of scientists obscured the truth on issues from tobacco smoke to global warming. Bloomsbury Publishing USA; 2011 May 31.

22Gornall J. Under the influence. BMJ. 2014 Jan 8;348.


24National Audit Office Evaluating government spending December 2021

25Slater J Fixing Whitehall’s Broken Policy Machine Policy Institute Kings College London

26Reynolds JP, Stautz K, Pilling M, van der Linden S, Marteau TM. Communicating the effectiveness and ineffectiveness of government policies and their impact on public support: a systematic review with meta-analysis. Royal Society Open Science. 2020 Jan 15;7(1):190522.

27Pechey R, Burge P, Mentzakis E, Suhrcke M, Marteau TM. Public acceptability of population-level interventions to reduce alcohol consumption: a discrete choice experiment. Social science & medicine. 2014 Jul 1;113:104-9.

28The Green Book

29The Magenta Book


The views and opinions expressed in this post are those of the author(s) and not necessarily those of the Bennett Institute for Public Policy.


Professor Dame Theresa Marteau

Director of the Behaviour and Health Research Unit at the University of Cambridge

Professor Dame Theresa Marteau is Director of the Behaviour and Health Research Unit at the University of Cambridge and co-chair of The Lancet Chatham House Commission on improving health post...

Back to Top